Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/29/20
Area Forecast Discussion
National Weather Service Caribou ME
1024 PM EDT Sun Jun 28 2020
.SYNOPSIS...
An upper low will over New England will prevail into mid week.
Unsettled weather will accompany it especially over western and
Downeast areas as surface low pressure develops off the
southern New England coast overnight and remains south through
mid week. High pressure approaches the region Thursday, followed
by a cold front from the north Thursday night and Canadian high
pressure for Friday.
&&
.NEAR TERM /THROUGH MONDAY/...
10 PM Update...
Steady rainfall ongoing across the w and nw areas this evening
w/intensity dropping off in the last few hrs. The radar showed
some enhanced echoes pushing nwrd w/GLM satl lightning product
showing increased potential for some lightning. Decided to keep
isold tstms in for central and northern areas overnight. Heavy
rainfall with the threat for overnight. Higher resolution
guidance having a hard time catching the individual heavier
cells. The latest RAP and HRRR were closest on grabbing the
general area of activity. Adjusted the QPF through 12z to catch
the higher totals across the w and nw areas.
Temps have fallen back into the 60s. Along the coast, temps
were in the upper 50s w/some stratus. Temps will drop a few more
degrees and then level off as clouds fill back in overnight.
Decided to areas of fog in for the coast and expanded this up
into the nw areas that received the heavier rainfall earlier.
Patchy fog elsewhere. Areas that see some partial clearing which
appears to be showing up on the latest ir satl imagery across
eastern areas could see a more widespread fog. Midnight crew can
monitor this further.
Previous Discussion...
Upper low continues to dominate the weather across the forecast
area through Monday. This will result in scattered showers and
isolated thunderstorms, mainly early this evening. Patchy fog is
once again expected tonight Downeast, especially along the
coast. As surface low develops to our South overnight, expect
the chance for rain to increase across Downeast areas by
daybreak Monday. The forecast soundings are showing deep moist
profiles across the western and Downeast portions of the
forecast area on Monday, with pwat values around 1.5". The
potential is there for locally heavy rainfall, especially from
the central Maine highlands through Downeast. The coldest air
aloft associated with the upper low on Monday remains to our
south and west. With more in the way of cloud cover on Monday
and easterly flow, potential for thunder looks lesser, and with
little in the way of significant SB CAPE expected, only a
mention of isolated thunder seems warranted. Across the far
north, expect lesser chances for rainfall on Monday, as deeper
moisture and forcing remains across the central highlands and
Downeast areas. High temperatures on Monday are expected to be
cooler as well, with more in the way of cloud cover expected,
along with northeast winds. This will confine high temperatures
mainly to the upper 60s to lower 70s across the region.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
Upper low pres will remained anchored ovr Cntrl New Eng thru
this tm, with this feature beginning to weaken by Wed. The sfc
low near Cape Cod will be strongest Mon ngt, with this system
slowly weakening ahead of the upper low beginning Tue as whats
left of low to mid layer baroclinicity gets used up.
This pattern will bring the best chc of shwrs and aftn/eve tstms
to Wrn and Downeast areas each day, with a definite diurnal sfc
htg component adding to the 18-00z 6hrly QPFs and somewhat to
the latter pts of the 12-18z and early ptns of the 00-06z QPF tm
frames. Hi temps will be held down most on Tue with the great
cld cvrg canopy arnd the upper low. Aftwrds, cld cvr will
begin to diminish ovr Nrn and ern ptns of the FA late Tue ngt
into Wed as the upper low nudges slightly further SSW. This will
likely result in an inverted Hi temp pattern ovr the FA with the
N warmest due to greater sunshine. Outside of Mon ngt, where NE
grad flow will be a little stronger to offset development, we
mention late ngt/erly morn patchy fog.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Shwrs and thicker cld cvr will exit to the S as whats left of
the upper low opens up and moves SE of Cape Cod. This will
allow much warmer 925-850 mb temps from Cntrl Can to enter the
FA from the NW for all of the FA. Any late ngt patchy fog will
rapidly dissipate within a couple of hrs after sunset, with very
warm aftn hi temps xpctd.
A fairly strong cold front from the N will enter Nrn areas of
the FA by erly Thu eve, crossing S of the Downeast coast by late
Thu ngt as a s/wv alf moves S from Nrn QB into the Ern Maritimes.
We indicate a chc of shwrs/tstms just ahead of this feature
beginning across the far N late Thu aftn and contg ovr Cntrl and
Downeast areas into the ovrngt.
Fri and and Sat look to be cooler and much more drier and
comfortable behind the front as sfc high pres from Hudson bay
prevails. Hi temps Fri and lows Fri ngt will be coolest with
recovering hi temps by Sat aftn. Sun will cont dry and a little
warmer yet with most lower trrn lctns N of the immediate coast
reaching back into the 80s as sfc winds become WSW with the sfc
hi crossing SE of the Gulf of ME.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
NEAR TERM: VFR at the Aroostook county terminals through early
this evening will give way to developing MVFR ceilings after
midnight. MVFR ceilings and scattered showers are expected on
Monday. Light south to southeast winds tonight around 5 kt.
VFR at KBGR/KBHB early this evening will give way to IFR in
developing low ceilings and patchy fog this evening. IFR
conditions will persist at those terminals through Monday
morning with improvement to MVFR Monday afternoon, with showers
expected. NE winds 5 to 10 kt expected on Monday.
SHORT TO LONG TERM: Mon Ngt - Wed Ngt...all TAF sites VFR late
morn into eve and MVFR/IFR late ngt into erly morn with ST clgs
in patchy fog. Clgs/vsbys briefly MVFR late morn into erly eve
with tstms/heavier shwrs. Lgt winds.
&&
.MARINE...
NEAR TERM: Wind/seas will remain below SCA levels through
Monday. Patchy fog and showers will reduce visibility to 1 to 3
NM at times through Monday.
SHORT TO LONG TERM: No dtmnstc pds of SCA seas xpctd attm,
although wv hts may come close attms ovr outer MZ waters. Went
with about 90 to 95 percent of blended wv guidance for fcst wv
hts thru these ptns of the fcst. Initially wvs will be comprised
of two spectral wv components Mon ngt and Tue, a short fetch 6
sec nwrd propagating group and a longer 10 to 12 sec background
NE propagating swell component with the swell component
prevailing from Tue ngt thru Thu.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service Des Moines IA
631 PM CDT Sun Jun 28 2020
.DISCUSSION.../Tonight through Sunday/
Issued at 216 PM CDT Sun Jun 28 2020
.Overview...
Our focus will remain set on storm development this evening and
overnight, where severe storms are likely across northern Iowa.
Periodic storms chances continue through much of the upcoming
week with hot and humid conditions each day.
.Details...
Morning convection gradually diminished across the state this
morning as it lifted north into central Iowa. The weak warm front
by early afternoon drapes across central into northern Iowa
roughly from Fort Doges to Marshalltown and down towards Ottumwa.
There have generally been two main areas for convection today,
the first across southern Iowa within the warm sector and the
second in west-central to north-central Iowa along the nose of the
frontal convergence. The latter has formed within the remnants of
the morning MCV where surface vorticity is maximized, resulting
in a funnel report.
Convection will continue to bubble across northern Iowa this
afternoon, with some strengthening expected around 00z a this
complex is met by advancing surface low pressure out of South
Dakota. Of the HREF suite, the HRRR is the furthest north with
solutions varying from southern Minnesota to southern Iowa. While
CAMs have struggled with convection lately, thus far the HRRR has
had the best handle on the overnight/morning convection. That
said, keying in on one solution over another is risky in this
environment and wouldn`t be surprised if a more southerly solution
unfolds, due in part to a PV anomaly over western Kansas which
could anchor convection a little south. Regardless of where
convective initiation occurs, severe storms will be well
supported. Model sounding indicate CAPE of 3500-4000+ J/kg with
steep mid level lapse rates. Shear is generally in the 30 kt range
to support initial discrete convection before upscale growth.
Hodographs exhibit excellent low-level curvature with 0-1 km SRH
of 150-200+ across northern Iowa. Initial discrete storms will
certainly have tornadic potential with threat transitioning to
wind and hail as storms grow upscale. Lastly, in addition to the
sever threat, heavy rain could result in flood concern across
northern Iowa with pwats of nearly 2 inches.
The rest of the period remains somewhat uncertain with periodic
chances for convection through much of the upcoming week. While
everyday will not be a washout, narrowing for windows for
convection continues to be a difficult task with subtle
shortwaves poorly handled by synoptic models. One area that has
become more clear is Wednesday as the western cut-off low moves
east. Model show some agreement in the progression of this system
and it appears that more severe weather could be possible, though
details are lacking. By the end of the week the pattern begins to
break down with drier conditions possible into the holiday
weekend.
Aside from the uncertainty in convective development, hot and
humid conditions will remain in place all week as warm gulf
moisture streams into the midwest. Daytime highs in the upper 80s
to low 90s with dewpoints in the low 70s will make it feel more
like the upper 90s to near 100. With this first extended hot, and
moreso humid, period of the year, heat safety will certainly be a
concern.
&&
.AVIATION.../For the 00Z TAFS through 00Z Monday evening/
Issued at 631 PM CDT Sun Jun 28 2020
Only concern for aviation weather in the TAF period is prospect of
TSRA and associated reduced vsby, low cigs, gusty winds overnight.
Unfortunately confidence in probability and location of any storms
is lower than usual, so have included VCTS groups over most likely
hours at all terminals except OTM, and will update/amend as needed
based on radar trends overnight. Any storms that do form will be
clear of the area by 12Z Monday, with only VFR conditions expected
thereafter.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
DISCUSSION...Hagenhoff
AVIATION...Lee
Area Forecast Discussion
National Weather Service Grand Forks ND
1003 PM CDT Sun Jun 28 2020
.UPDATE...
Issued at 957 PM CDT Sun Jun 28 2020
Line of storms has develop from Bismarck to SD border which is
farther south of previous thinking. This activity will spread
eastward across southern ND moving into SE ND weakening as it
does.
UPDATE Issued at 638 PM CDT Sun Jun 28 2020
North south boundary has been the focal point for thunderstorms
across central ND this afternoon and evening. Across the eastern
portions of the state breezy and warm conditions persist with
temps in the mid to upper 80s and dew points in the mid to upper
60s. CAMs continue to indicate the activity in the west will stay
west until short wave energy evident in western SD convection
pushes east merging with or aiding in development of more storms
on the southern end of the convergence line in western ND. This
activity will then move into western portions of the CWA somewhere
in the 12AM to 3AM time frame. Shear is expected remain weak with
HRRR and NAM indicating 0-3km values less than 25kts. Combined
with increasing CIN during the early morning hours convective
activity should be on a downward trend in strength as it moves
into the area. That said still too early to rule out any wind
potential with respect to the severe threat.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 240 PM CDT Sun Jun 28 2020
Hot and gusty conditions will dominate the forecast through the rest
of the afternoon. Southeast winds are already gusting over 35 mph
and will continue until around sunset. Temps will max out in the
upper 80s to lower 90s, with heat indices in the mid 90s, warmest
near central ND.
CAMs are still trying to resolve the evolution of convection
expected to initiate in western and central ND along an north-
south oriented stationary/quasi warm front. The front sits just
west of the Turtle Mtns south to near Dickinson. Supercells and
multicell clusters are expected to develop along this front mid to
late afternoon, although storm trajectories should be northerly
amidst deep layer southerly flow. However there may be the
tendency for new updrafts to propagate east or southeast which may
bring these strong to severe storms closer to the Devils Lake
basin (namely Benson and Towner counties) around or after sunset.
Should this happen, the threat for very large hail, gusty winds,
heavy rainfall, and a slim chance for a tornado.
12Z HREF continues its trend of UH tracks into the Devils Lake
basin and now the James River Valley, especially after 1 AM as a
shortwave moves through western ND. Despite moderate to strong
instability feeding storms (including high DCAPE), deep layer
shear is expected to be lacking, especially east of central ND.
Early morning storms are likely to be linear, and with the a
window of DCAPE feeding into convection, high wind gusts with
thunderstorms will be possible. Given the trends of latest hires
guidance, keeping a slight chance for storms mentioned in the
forecast in these areas, some of which may be severe.
Monday will be similar to today, except may a little less wind and
more heat. Temperatures and dew points should be a touch higher
tomorrow as thermal ridge edges closer over the area and moisture
advection continues. Highs in the upper 80s to mid 90s Monday
combine with dew points in the 70s to bring heat indices well into
the 90s for the Red River Valley and west. Some locations in
southeast ND could see heat indices exceed 100 degrees for a brief
period in the afternoon, which may require heat headlines. Storm
chances again exist for portions of eastern ND late Monday, some of
which may be strong to severe bringing hail and gusty winds.
.LONG TERM...(Tuesday through Sunday)
Issued at 240 PM CDT Sun Jun 28 2020
Tuesday and Wednesday...Upper low/trough over the western CONUS
becomes more negatively tilted by Tuesday. There will continue to be
warm, moist air moving into the Northern Plains ahead of the surface
trough, although think that convection will remain capped for at
least part of the day. Several weak lead shortwaves moving through
should push the surface trough axis into eastern ND by evening, and
will be the focus for strong to severe thunderstorm development.
Instability will continue to be very strong with over 3000 J/kg of
ML CAPE possible. On the other hand, with the main upper system
still well to the west the deep layer bulk shear is very weak. Some
pulsey severe storms and heavy rain from slow movement seem most
likely at this point. The upper ridge will move further east by
Wednesday, with improved upper level flow and stronger deep layer
shear. Hard to tell the exactly how the instability on Wednesday
will play out given earlier convection, but PWAT values remain in
the higher percentiles according to the NAEFS and chances continue
to remain high for precipitation.
Thursday through Sunday...The main upper trough lifts northward into
Canada on Thursday, leaving southwesterly flow aloft turning into a
ridge for the end of the week. Weak high pressure will keep things
dry and warm for Thursday before conditions heat up more for Friday
as south winds return. Independence Day looks quite toasty with high
heights, then ridge riders possibly bringing some convection,
although placement and timing is impossible to tell at this point.
Heat and thunderstorm chances continue into Sunday although
moderating a bit as the ridge starts to break down.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 638 PM CDT Sun Jun 28 2020
Wind continue to gust from 20 to 35kts at all TAF sites. Will see
gusts wane this evening. Will keep the mention of thunder out of
all tafs for now. There remains the possibility between 6 and 12Z
at DVL, GFK and FAR. Though confidence is low in occurrence. Will
keep the mention of MVFR CIGs for the early morning hours.
Tomorrow should see less wind.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
UPDATE...JK
SHORT TERM...CJ
LONG TERM...JR
AVIATION...JK
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
650 PM CDT Sun Jun 28 2020
.SHORT TERM...(This Evening through Monday Night)
Issued at 325 PM CDT Sun Jun 28 2020
Short term forecast remains largely focused on the remnant MCV that
is moving its way north-northeastward across the area. GOES-16 water
vapor imagery shows the spatial coverage that this feature has,
causing cloud coverage from eastern SD, through southern MN and down
into western IL. The trailing southwestern edge of the cloud cover
will continue on the decline, allowing daytime heating to resume
throughout the rest of the afternoon.
With dewpoints as of 3 PM in the mid 60s to lower 70s and
temperatures increasing with cloud coverage dissipating, it is no
surprise that ample CAPE (~3000-4000 J/KG) will be parked over the
area this afternoon. Effective bulk shear values are highest over NW
IA, where 40+ knots are available, but the shear drops off as we
head into the evening making organized storms more difficult to
maintain. Given the large amounts of instability and good shear
early on, if any storms are do form in this environment they will be
able to produce hail to the size of golf balls. A tornado in NW IA
can not be ruled out early on either, as low LCLs coincide with
areas of enhanced 0-1 km storm relative helicity. As storms begin to
lose their composure, DCAPE values greater than 1000 J/KG will shift
the risk towards more of a wind threat as storms track eastwards
along the anticipated cold pool. Vast majority of HREF members had
storms initiating in NE Nebraska, but the HRRR runs since this
morning have been putting initiation in NW Iowa. Most high
resolution guidance didn`t handle the movement of the MCV very well
this morning, so tend to trust the evolution of the HRRR which
favors NW Iowa.
If there are any lingering storms Monday morning in NW IA and SW MN
courtesy of the low level jet, they will continue to trail off to
the east leading to a hot and humid day. Under southwesterly flow
aloft, south-southeasterly flow near the surface will remain in
place throughout the day, with gusts up to 25 mph under a strong
inversion aloft which should prevent any afternoon storms from
firing. With weak low-mid level cloud coverage, temperatures will
climb into the low to mid 90s with dewpoint temperatures rising into
the low to mid 70s. Heat index values are looking warmest primarily
west of the I-29 corridor, where heat indices greater than 100 are
possible with some pockets approaching 105. Have collaborated a heat
advisory with neighbors for areas where this is most likely, but may
need to be expanded. The winds will calm down a bit into the
overnight period, with low temperatures staying rather warm in the
low to mid 70s.
.LONG TERM...(Tuesday through Sunday)
Issued at 325 PM CDT Sun Jun 28 2020
The trough over the western CONUS remains in place, leaving us under
south-southwesterly flow aloft along with a strong inversion in
place. Temperatures will be a little cooler, with highs in the upper
80s to lower 90s and heat indices currently expected to remain
largely in the 90s. As the trough axis wobbles its way closer to our
area, the surface low will get close to our area creating a strong
pressure gradient which will cause our winds to remain breezy with
gusts in the 25-30 mph range. The surface low is currently expected
to break off into two lows, one heading to our south and the other
staying well off to our north.
The cold front being dragged eastwards by the southerly low will
likely set off scattered showers and thunderstorms in central SD
during the afternoon, and will attempt to fire off more storms in
eastern SD overnight. While CAPE values exists out ahead of the
front ~3000 J/KG, the best combination of good shear (40-45 knots)
and CAPE (~2000 J/KG) exists in an elevated narrow corridor behind
the front. Some frontogenesis and positive vorticity advection will
be aiding these storms aloft, and working together with steep mid-
level lapse rates will likely result in a couple strong to severe
thunderstorms. This threat is highlighted nicely in SPC`s day 3
severe weather outlook.
Scattered shortwaves continue to move overhead throughout the day on
Wednesday, keeping chances for showers and thunderstorms into the
early evening. Drier air and upper level ridging moves in early
Thursday morning, which should keep rain chances low into the
weekend. A stray showers cannot be ruled out for 4th of July
fireworks at this point although it is looking unlikely, with
otherwise warm and moderately breezy conditions expected for the
holiday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 641 PM CDT Sun Jun 28 2020
South and southeast winds will remain gusty through sunset. These
winds continue overnight, but gusts will decrease in frequency and
strength. Scattered thunderstorms are possible in northwest Iowa
this evening into the early overnight, including for locations
such as KSPW (Spencer IA). Shortly after sunrise, gusty south
winds again become gusty with mostly cloudy skies.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Heat Advisory from 1 PM to 8 PM CDT Monday for SDZ038-039-
052>054-057>061-063>066-068-069.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...APT
LONG TERM...APT
AVIATION...VandenBoogart
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
735 PM CDT Sun Jun 28 2020
...Aviation Update...
.SHORT TERM...(This evening through Monday)
Issued at 259 PM CDT Sun Jun 28 2020
Biggest problem in the short term will be determining if a stray
thunderstorm develops over the CWA or moves in from the west this
evening.
Going with a dry forecast this afternoon/tonight but chances are not
exactly zero as an isolated shower/thunderstorm could pop up.
Coverage would be extremely scant, though. Although the 12Z run of
the HRRR shows a couple of pop-up thunderstorms in our southern CWA
and the NAMnest tries to give us a little convection in our east, I
suspect that we will be too capped to allow much activity to
develop, despite the high CAPE environment. Our best shot at an
isolated thunderstorm would be in our far east/northeast to near
GI/Hastings, it appears. Developing cumulus today should have little
chance of much vertical development, however. Hazy skies are largely
a result of some Saharan sand. Some hi-res/short term models bring
dying convection close to our western CWA this evening, but the 850
mb theta-e ridge will likely be skewed just east of our CWA, and
will offer little help to struggling convection in western/central
Nebraska. With higher dewpoints will come low temperatures remaining
in the 70s for most tonight.
For Monday/Monday evening, 700 mb temps will be in the 15-16C range,
and should pretty much quell any chance of thunderstorm development
under strong subsidence. Dewpoints will be every bit as high as
Sunday, with heat index pushing to near 100 or so, especially in our
east, as our actual high temperatures reach well into the 90s.
Models are giving me a bit of a cool-down for 850 mb, and even
models that have done well on our recent hot days, are giving me
temps cooler than our previous forecast. I`m not comfortable
knocking down temps all that much as it looks like we could have
some feedback issues going on.
.LONG TERM...(Monday night through Sunday)
Issued at 259 PM CDT Sun Jun 28 2020
Biggest problem will be determining storm chances and potential
severity for Tuesday/Tuesday night with potential shortwave trough
and approaching cold front and trough/dry line.
For Tuesday/Tuesday night, a spoke of energy rotating around the
broadening northwest United States trough will give us a shot at
some thunderstorms, possibly severe. The focus of synoptic support
remains northwest/north of our CWA for the most part but we could
have foci for convective development despite the limited help
synoptically. A strong baroclinic zone will exist Tuesday along and
ahead of a cold front, with a possible pre-frontal trough/dryline to
potentially complicate things. MLCAPE of 3000+ J/kg There could be a
triple point scenario somewhere near our area as well, possibly in
our western/northern CWA, although deep layer shear does not look
incredibly impressive. A hindrance to convection will be 700 mb
temps of 15+C during the afternoon, but should give way to cooler
temps by evening with diurnal cooling and height falls, and could
allow elevated convection to occur. Nocturnal convection may be
aided by low-level convergence of a low-level jet in the vicinity.
Ensembles support a solution showing strengthening upper level
ridging for the latter half of the week, ensuring warmer than normal
temps into the 90s and low chances of thunderstorms/precip. Thursday
would stand the very best chance of being dry of a forecast already
on the dry side as a solid surface high builds in behind a cold
front.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday)
Issued at 734 PM CDT Sun Jun 28 2020
General overview:
Confidence is high in VFR ceiling/visibility through the majority
of the period, and in rain/thunderstorm-free conditions
throughout. That being said, there are a few pesky question marks
to consider (covered in more detail below). But before getting to
those, will cover surface winds and visibility trends. Surface
winds: Fairly straightforward. Direction will be remarkably
consistent (from the south-southeast), with sustained speeds
commonly 10-15KT and highest gust potential mainly 20-25KT and
overall-strongest Monday afternoon. Visibility: Thanks to haze
from Saharan dust, especially KGRI has been experiencing low-end
VFR visbility for several hours now, and this will probably
persist into much of at least the first half of the period. Not
anticipating MVFR, but will run with 6SM HZ to cover this. Now
onto the main uncertainties/possible pitfalls:
1) Some ceiling uncertainty:
Some models/guidance are strongly hinting at MVFR stratus ceiling
developing early Monday morning and perhaps lingering well into
the day, while others are much-less aggressive. It`s a really
tough call at this point to say whether this MVFR will actually
develop, and if so, for how long. Am certainly not ready to run
with prevailing MVFR yet, but feel it`s prudent to at least hint
at this possibility. As a result, have introduced scattered MVFR
clouds starting at 09Z. Should these lower ceilings develop in the
morning, they would most likely scatter out and/or lift to VFR
levels during the afternoon, but could remain low-VFR.
2) Possibility of very marginal low level wind shear (LLWS)
overnight:
Previous TAFs carried a formal LLWS mention, but latest guidance
has backed off the overall-shear magnitude within the lowest few
thousand feet above the surface, maxing it out closer to 25KT than
30+KT. As a result, opted to remove the official mention of LLWS
with this issuance, but this will need monitored closely for
possible "last minute" re-inclusion.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...Heinlein
LONG TERM...Heinlein
AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Goodland KS
533 PM MDT Sun Jun 28 2020
.SHORT TERM...(This evening through Monday)
Issued at 137 PM MDT Sun Jun 28 2020
19Z UTC Water Vapor Imagery and RAP analysis continued to indicate
broad westerly flow aloft over the CWA with short wave trough
moving east across central Kansas, with much of CWA under the
effects of subsidence behind it.
At the surface flow aloft has become southeasterly with convergent
area/trough once again setting up in western CWA. Have seem
several attempts at convective initation, but as of now storms
have not been able to develop.
Main forecast concerns will be precipitation chances tonight and
the heat and fire wx.
While recent attempt at thunderstorms have failed, expect
persistent forced ascent in eastern Colorado to get the ball
rolling on a few thunderstorms by 23Z. As has been the case,
strong cold pools likely. Instability weaker in formation area and
CINH (especially ML) is much stronger to the east. Instability
profiles, coupled with weaker low level shear profiles makes it
seem doubtful that another MCS will march across the area. Expect
a few storms to make it near the KS/CO border, with CINH
increasing and cold pools likely surging ahead of the cells
limiting the chances for precip to continue eastward are slim.
Intense heating and convergence along dryline could possible spark
a storm or two tomorrow afternoon. But with any frontogenetic
forcing likely occurring on the dry side and strong CINH in the
moist sector, seems doubtful anything will develop.
Strong consensus that temps will hit the century mark in several
locations, especially to west of dryline where dewpoints fall into
the 30s. Winds will increase after 20z in this area, resulting in
a window of critical fire weather conditions.
.LONG TERM...(Tuesday through Sunday)
Issued at 156 PM MDT Sun Jun 28 2020
Not much has changed since the last discussion. An upper-level deep
trough moves out of the Great Basin and over the High Plains during
the middle of the week. Tuesday, a surface front, associated with
this trough, will move through the Tri-State region; producing a
chance of showers and thunderstorms. After this front moves through
the area an upper-level ridge builds into the area from Mexico and
influences the area with dry conditions through Thursday. Temps will
remain in the above normal range of the middle 80s to the middle 90s
for the rest of the period; however, they will be slightly cooler
than around 100 we will see on Monday. In addition, the dry
conditions will produce elevated to near critical fire weather
conditions, mainly for the west portion of the Tri-State area
through through Friday.
For the the 4th of July weekend, the models are showing minor
shortwaves troughs transiting within the mid-level flow that could
aid in the development of showers and thunderstorms over the area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 532 PM MDT Sun Jun 28 2020
VFR conditions are expected to prevail through the TAF period at
KGLD and KMCK terminals. Southwest winds will persist through
midnight at both sites, becoming southerly around 9kts. Winds may
briefly become westerly around 16Z, returning to southerly Monday
afternoon at 15kts gusting to 23kts.
At KMCK, low level wind shear will be possible from around 05 to
10Z. Wind shear will be from 180 degrees at 35kts around 05Z,
becoming 190 degrees at 40kts around 07Z. Winds will become
southeasterly again through the day Monday.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Red Flag Warning from noon MDT /1 PM CDT/ to 8 PM MDT /9 PM CDT/
Monday for KSZ001-013.
CO...Red Flag Warning from noon to 8 PM MDT Monday for COZ252>254.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...BW
AVIATION...AW
Area Forecast Discussion
National Weather Service Wilmington NC
951 PM EDT Sun Jun 28 2020
.SYNOPSIS...
Weak high pressure will remain over the area through tomorrow. A
series of upper disturbances will move across the region tonight
through midweek, producing daytime as well as nigh-time
scattered showers and thunderstorms. A weak front will move in
from the north, stalling in the region by and through the mid-
week.
&&
.UPDATE...
Will be dealing with a broken line of thunderstorms arcing it`s
way across the FA for the remainder of this evening. The leading
edge of this line extended from St Pauls across Fairmont to
Mullins and then arcing back across Evergreen to Olanta. An
isolated strong to severe thunderstorm along this broken line
remains a possibility until this activity pushes off the
Carolina Coasts. Will re-adjust POPs and sky cover to account
for the current and future movement of this activity.
A steady state of light showers or stratiform light rain
extends 20 to 40 miles behind this leading edge of convection.
This activity is making a steady run to the East-Southeast at 20
to 30 mph and should reach and push off the Carolina Coasts
between 1030pm and 1130pm. The back edge of the stratiform light
rain will follow but will be dissipating as it moves across the
FA. Will likely carry isolated POPs for the reminder of the
overnight for all locations after the main threat and stratiform
light rains push off the coast.
Made some adjustments to tonights lows as well as overnight hrly
temps and dewpoints, especially locations that experienced
rainfall.
Some tweaking of the winds over the area waters overnight, with
synoptic winds generally SW-WSW at 10 to occasionally 15 kt. A
few gusts could reach 30-35 kt associated with the convection
that initially moves off the coast. Which will and may require
MWS or SMW. Seas generally 2 to 4 ft, with the 4 footers located
across the outer waters, 15 to 20 nm out, off Cape Fear south to
Murrells Inlet.
&&
.NEAR TERM /THROUGH MONDAY/...
Likely an active pattern though some vexing differences in opinions
between models persists. Local mid level flow will be WNW to NW
around a large cutoff over the Northeast. A convectively generated
vorticity max will move towards the area this evening and right away
guidance is struggling to depict what happens as the system crosses
the Appalachians. The WRF continues to show a rather strong
convective signal in what looks very much like an MCS that
transitions into a training flash-flood setup not unlike the current
radar depiction across parts of TN/KY making this solution certainly
appear possible. The rapid update and radar ingestion of the HRRR
appears a more likely scenario in that it depicts some robust
convection entering our NW zones close to sunset but then shows a
weakening trend as instability wanes diurnally. Our far southern
zones may not pick up much rain at all. I did chose to keep POPs in
the forecast all night though as we may have a healthy outflow
boundary lying NW to SE across our CWA. This boundary may end up
serving as a convective focus as will the sea breeze...the
intersection of the two possibly in the Cape Fear Region where POPs
have been raised.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
An upper-level cut off over the northeast US will stall and provide
weak pulses of energy out of the NW rotating downslope of a weak
upper ridge over the central US. Showers and thunderstorms will be
possible both Tuesday and Wednesday in conjunction with afternoon
instability. A slightly more potent shortwave will move into the
area on Wednesday evening and help with the development of late
afternoon thunderstorms which could spill over into the early
evening with lingering elevated instability. Temperatures will be in
line with climo both days.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Cutoff low will become absorbed in the large scale flow on Thursday.
Will maintain thunderstorm chances on Thursday as the positively
tilted trough remains elongated over the Mid-Atlantic and Northeast
US. Storms will be isolated in nature as current models show dry air
may lead to limited coverage. Models continue to diverge on a
solution after Thursday with both showing a weak frontal boundary
pushing south out of the Great Lakes region. Thunderstorms will be
likely along this frontal boundary as it progresses. The GFS model
shows the front slowly progressing into the area on Friday while the
ECMWF shows the front well south of the area and a dry air mass
dominating the weather on Friday and Saturday. This uncertainty
remains large and will prefer to lean toward the front stalling in
or just south of the area as climo and previous weather pattern
observations suggest. Sunday will likely introduce higher storm
chances as moisture returns from the south despite the boundary
weakening.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
A disturbance aloft has helped ignite scattered showers and
thunderstorms across the Carolinas early this evening. As of
00Z, the leading edge of the main cluster of storms extended
from Lumberton across the NC-SC border and Florence to Columbia.
This cluster is pushing ESE at 30 mph and will reach and push
across the coastal terminals between 2z and 4z. Expect brief
periods of MVFR/IFR conditions with a few of the stronger storms
producing wind gusts of 40+ kt. After 06Z, convection should
settle down with only isolated activity at best. Convection will
likely re-fire late Mon morning or early aftn as residual
dynamics aloft press southward and have indicated this potential
with Prob30 groups.
Extended Outlook...Expect possible MVFR/IFR conditions from
isolated to scattered showers and thunderstorms each day and
night through Wednesday. This the result of a series of
weak disturbances aloft moving across the area. Early morning
MVFR from BR remains possible.
&&
.MARINE...
Southwesterly flow in the 10-15kt range will be the general rule
through Monday night. It may grow lighter at times however as lower
pressure ridge into the Carolinas trailing from an area of low
pressure in the Northeast. 5-6 second wind waves along with a
relatively weak 10 second SE swell will generally yield 2-3 ft
seas.
Offshore flow on Tuesday will continue at 5-10 knots with a typical
Bermuda swell at 2 feet and 8-9 seconds. As low pressure over the
Northeast US exits into the North Atlantic, southerly winds return
to the area. Winds will remain 10-15 knots through the middle of the
week ahead of an approaching weak frontal boundary. Lots of
uncertainty exists with the position of the front and the associated
winds. Regardless, wind directions and speed don`t look to be
impactful. The main threat for mariners this week will be the chance
of thunderstorms each day through Saturday.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...MBB
UPDATE...DCH
NEAR TERM...MBB
SHORT TERM...21
LONG TERM...21
AVIATION...DCH
MARINE...DCH/MBB/21
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
948 PM CDT Sun Jun 28 2020
.UPDATE...
946 PM CDT
Main update this evening was to back off PoPs through early Monday
for a primarily dry forecast. Previous high resolution CAM
guidance that had brought convection to parts of northwest and
north central Illinois toward and after daybreak was far too
aggressive with upstream convection. A broken arc of thunderstorms
did finally develop recently over northeast Iowa. However,
steering flow is off to the northeast, so unless the thunderstorms
quickly congealed and developed a cold pool, would expect them to
continue tracking off to the east-northeast and stay north of our
latitude. As such, the new 00z CAM guidance has supported the idea
of a primarily dry overnight period. Did maintain slight chance
PoPs for parts of the CWA well after midnight owing to the
impressive MUCAPE reservoir sampled on the 00z DVN RAOB.
Looking ahead to Monday, it appears we will destabilize quickly
and erode capping. However, with the increasing likelihood of a
drier start to the day, as well as general lack of large scale
forcing mechanism, favored area for CI toward mid day may be in
the vicinity of lake breeze convergence and perhaps differential
heating boundaries as cumulus quickly blossoms. As a well modeled
MCV crosses the MS River Valley toward Monday evening, that should
provide a bump in large scale forcing to increase convective
coverage in the mid to late afternoon to scattered (40 to perhaps
60%). A steeper mid-level lapse rate (>7C/km) plume will be over
the area during peak heating, along with steep low level lapse
rates. Temps inland of the lakeshore rising to near/around 90 and
dew points in the 70s should yield large MLCAPE potentially near
or even above 4000 j/kg.
Therefore, despite generally sub-marginal deep layer shear,
updraft acceleration from the large CAPE plus steep low level
lapse rates should yield an isolated downburst wind threat from
the collapse of tall cores. Can`t rule out isolated marginally
severe hail from the deepest convection. In addition, very slow
and erratic storm motions as has been typical the past few days
amidst PWATs over 1.75" will support a localized flash flooding
risk. High moisture content will be another element in support of
isolated damaging wind potential due to precip loading of
downbursts. If we can add (subtract) a few more degrees to the
high temps tomorrow, which will depend on how quickly cumulus
field blossoms, then heat index values of near/over 100F will be
more (less) common.
Castro
&&
.SHORT TERM...
259 PM CDT
Through Monday night...
As has been the case, the forecast emphasis was on deciphering
the primary thunderstorm chances and coverage. After spotty storms
through early evening, chances then start to increase overnight
into Monday morning, with at least scattered thunderstorms looking
likely Monday afternoon and early evening. Similar to recent
convective episodes, locally gusty winds and heavy rain will be
probable with any storms. Also of note on Monday will be potential
for heat index readings to peak around 100.
An early reaching of the convective temperature by noon resulted
in a scattered of showers and a couple storms, but also brought
ample cumulus and some cold pooling, together slowing heating.
Thus coverage has dropped off as of 300 PM. Additional isolated
storms are possible through the early evening with the high
boundary layer moisture, renewed heating with some clearing, and
subtle wind discontinuity foci. There should be a relative minimum
though in chances from roughly 8p-1a before gradually increasing
chances overnight with strengthening warm advection aloft. The mid
to upper level ridging will be quite stout, with the warm frontal
zone at 850 mb lifting into this. This will steer steep lapse
rates from roughly 750-550 mb into north central Illinois
overnight. So it will be a question whether any scattered elevated
convection can realize those lapse rates for a few strong to
possibly severe storms. Convection allowing models (CAMs) have
trended slightly downward with their footprint overnight, but
tough to say for certain if the mid-level ridge of the elevated
instability (MUCAPE > 1500 J/kg) will win out into north central
Illinois.
Any elevated activity will likely be on a downward trend by mid-
morning, especially with any short wave/MCV focus likely moving
east-northeast away from the area. However, any outflow boundaries
may serve as a focus into the afternoon, in tandem with the low-
level frontal zone which will be inching northeastward over the
area. Confluence/convergence along this is not predicted to be
strong, although it may not need to be as forecast soundings from
the NAM show the convective temperatures in the upper 80s reached.
In addition the air mass along this frontal zone will be
characterized by dew points in the mid 70s given upstream
observations near Kansas City today. It may not take much impetus
in the low and/or mid-levels to spark convection Monday afternoon,
but it`s another messy setup with a domino effect to any
mesoscale features in advance. That will also impact temperatures
on Monday that have the potential to warm to the lower 90s. If
they can, heat index readings will eclipse 100. But confidence is
not high on that given the likelihood of at least morning clouds
and the propensity to convect by mid afternoon if pockets of
strong heating do materialize.
Convection that does develop Monday afternoon will be capable of
strong winds and local flash flooding, as storm motions will again
be on the slower end of the spectrum. With mlCAPE values expected
to reach 1500-2000 J/kg, the potential for stronger downbursts is
there, especially if there is any remnant MCV artifact helping to
drive things. Convection should again gradually taper through the
evening, though a mid-level disturbance approaching from the
southwest will keep some chance into the overnight.
MTF
&&
.LONG TERM...
257 PM CDT
Tuesday through Sunday...
Warm, humid, and unsettled conditions look to remain in place through midweek
with persistent east to southeasterly low level flow. As winds gradually turn
more east to northeast later in the week, temperatures may not fall much but
dewpoints and associated precip chances may decrease a bit. Midwest upper
level ridging will limit the passage of larger scale synoptic systems through
the area, so convective trends will mainly be driven by mesoscale effects and
diurnal heating.
Tuesday morning could see one of the more pronounced mesoscale systems over the
area with multiple models developing an MCV upstream and lifting it into the
ridge that sits overhead. Model signals suggest this activity may be waning
during the early morning, likely due to a combination of unfavorable diurnal
timing and the influence of the ridge, but the lingering circulation appears
poised to tap into afternoon heating and generate renewed development Tuesday
afternoon. Remnants of the circulation may even persist into Wednesday and
support additional development that afternoon before dropping south out of the
area.
Following the departure of the MCV, by Thursday into the weekend winds appear
favored to back more easterly to northeasterly as mentioned above. With a
somewhat drier boundary layer, precip chances and overnight lows appear
correspondingly lower compared to earlier in the week, but the associated
reduction in cloud cover should keep afternoon highs in the mid-upper 80s to
lower 90s...though cooler by the lake.
Lenning
&&
.AVIATION...
For the 00Z TAFs...
Aviation forecast concerns:
* Timing/coverage of SHRA/TSRA potential through the period,
focusing on Monday afternoon/early evening.
High pressure was centered from the central Great Lakes northward
late this afternoon, while a warm/humid air mass covered much of
the Corn Belt to the south and west. Old synoptic boundary which
sagged across the local area Friday-Saturday, while somewhat
diffuse, appears to extend from southern MN across northern IL to
central IN, while an old consolidated outflow boundary from a
couple rounds of organized convection was farther to the south
from western IA, across northeast MO into southern IL. Air mass
from Chicago west and southward is characterized by temps in the
mid-80s and dew points around 70, with conditionally unstable
conditions topped by somewhat dry mid-level air and weak mid-level
lapse rates. This has generally prevented organized convective
development across the area this afternoon, though area of
slightly enhanced cumulus along boundary from near KRFD to KDPA
to south of KGYY could potentially produce an isolated SHRA or
TSRA early this evening before sunset, as tail of mid-level trough
lifting northeast across MN transits far northern IL. This
appears to be fairly low probability however, and even lower
prospect for directly affecting KRFD, KDPA or KGYY.
The next potential period of SHRA/TSRA would be toward/after
sunrise Monday morning, with some guidance depicting a decaying
MCS sliding east-southeast along the warm frontal zone. 3 km WRF
and some of the other WRF-based CAMS depict this, while more
recent HRRR and RAP runs have backed away from this. Certainly
potential for elevated convection to develop overnight across
parts of IA, with southwesterly low level jet focused there atop
aforementioned low level boundaries, though with better mid-level
support lifting northeast into MN am more inclined to follow drier
HRRR/RAP scenario at this time.
Greatest potential for TSRA development across the terminals
appears to be Monday afternoon, with most guidance developing
convection along a combination of northeastward moving
front/outflow boundaries and lake breeze boundary during peak
diurnal heating. Some indication that there could be some isolated
updrafts developing by late morning in the vicinity of the lake
breeze boundary (which sets up early with synoptic southeast
flow), but there is a much stronger signal with approaching
surface boundary from about 20Z/3 PM onward as instability peaks
during the mid-late afternoon. Relatively light mid-level winds
would indicate slow cell movements, likely with considerable
outflow boundary interaction. For this reason, threat of TSRA
would likely linger into the early evening before instability
decreases toward/after sunset. This would also result in a
somewhat chaotic wind direction scenario modulated by what could
be numerous gusty outflow boundaries. Outside of convective
influence, wind should generally remain from the east-southeast.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1026 PM EDT Sun Jun 28 2020
.SYNOPSIS...
A shortwave will move across the region this evening and tonight.
Unsettled weather continues through the middle of next week as
an upper low becomes stalled over New England with several weak
disturbances moving across the Mid-Atlantic states.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 1025 PM Sun...Shortwave and associated vort max is
positioned along the Appalachians this evening per WV imagery
and continues to slow dig towards the Carolinas. The continued
southward trend in guidance with the convective cluster over the
NC/SC border and only very spotty shower activity over our CWA.
Short range guidance (including the 01Z HRRR to a lesser degree)
continued to initialize this feature too far north, and do show
a second round of showers and storms diving across the same area
overnight as the shortwave digs into the region. Think this will
also track further south than indicated but uncertainty is high,
so have a broader than normal slight chance PoP mainly from
Highway 264 south. Best chance of activity, if any, will be
along or south of Highway 70.
The North Carolina Department of Environmental and Natural
Resources has issued a Code Orange Air Quality Action Day for
Fine Particulates through midnight tonight for the Saharan
desert plume which will move over the area through at least
tonight. The large swath of Saharan dust is expected to create
hazy skies and unhealthy breathing conditions where the dust is
most concentrated.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
As of 330 PM Sun...The aforementioned shortwave will pass
overhead around sunrise, sliding south and east of the area
with subsidence developing behind it late morning through
midday. This subsidence will keep mainly dry conditions in place
through the morning hours and potentially into the early
afternoon, but will weaken by mid afternoon, allowing the
chance for thunderstorms to come back into the forecast.
Afternoon precip focus will be mainly along and ahead of the
sea breeze, which will once again be slow to progress inland in
WNW low level flow. Ample instability will be in place, but
limited shear and DCAPE will keep the severe threat low overall.
Temps near normal will continue.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
As of 4 AM Sunday...A trough will dig down the eastern seaboard
through much of the coming week, bringing off and on scattered
showers and storms to the region.
Monday Night through Thursday...Upper level low pressure will
close off from the background westerlies and drop over the
Northeast and Mid Atlantic region, with several weak shortwaves
traversing the general troughing that will extend over the
Carolina Coast. Ocnl periods of unsettled weather will prevail
through much of the week, though not a washout by any means.
Will forecast pops in the slight chance to chance range, with
the highest chances coinciding with typical diurnal showers and
storms each afternoon, highest chances along typical sea/sound
breeze zones and Coastal Plain region. Relatively seasonable
airmass prevails at the surface as Bermuda High continues to
ridge in the from east with troughing inland, and daily temp
trends will be primarily dependent on precip timing and cloud
cover.
Friday and Saturday...The upper low over the Northeast region
fills Thursday with the upper trough axis sliding to the south
by Friday, which may lead to lower precip chances late in the
week. However, guidance is showing lingering troughiness over
the lower Mississippi and Tennessee River valleys may develop
into another closed low late in the week. Depending where this
sets up, ENC may remain in a more unsettled pattern, but as with
most closed lows, predictability is low, especially this far
out.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Short Term /through Monday/...
As of 740 PM Sun...VFR at all sites this evening with
increasingly isolated showers moving into the coastal plain this
hour. Shortwave trough over the Appalachians in VA will continue
to drift south tonight and help nudge convective activity
currently over northern SC east tonight towards coastal NC.
Guidance trends have been slower and further south in regards to
convective activity, and it appears increasingly likely PGV/ISO
will get through the evening without much activity. OAJ remains
the most likely and maintained the TEMPO group with a minor
slowdown in timing. Typical convective-associated restrictions
are expected to last less than an hour. VFR conditions prevail
in this feature`s wake overnight into tomorrow with subsidence
aloft into the first half of Monday. Some sea breeze convection
could introduce potential impacts for OAJ/EWN tomorrow
afternoon.
Long Term /Monday Night through Friday/...
As of 430 AM Sunday...Unsettled weather will prevail much of
early to mid week, with periods of sub VFR possible.
&&
.MARINE...
Short Term /through Monday/...
As of 340 PM Sun...Broad low pressure stretching from New
England to the Mid-Atlantic and high pressure across the Gulf of
Mexico and Caribbean will keep moderate WSW to W winds in place
through tomorrow. Gusts to 20 kt this afternoon will bring seas
to 3-5 ft for areas exposed to SSW wind swell this evening, but
seas will subside some overnight as the windswell diminishes,
and 2-4 ft seas prevail once again on Monday.
Long Term /Monday Night through Friday/...
As of 430 AM Sunday...A trough will persist near the area
through the long term with generally light winds around 15 kt or
less. Wind direction will depend on the location of the trough
with mainly a southerly direction with the trough north of the
waters, however the trough may sag south of the area Tuesday
with winds briefly becoming N to NW, and may sag back into the
waters again Thursday. Seas expected to remain around 2-3 ft
through the period, occasionally building to 4 ft across the
outer portions of the central/southern waters.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...MHX
NEAR TERM...MS
SHORT TERM...CB
LONG TERM...SK
AVIATION...SK/MS
MARINE...SK/CB
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
700 PM CDT Sun Jun 28 2020
.SHORT TERM...(This evening through Monday night)
Issued at 401 PM CDT Sun Jun 28 2020
MCV moving into the Mankato area will be the focus for
thunderstorms this afternoon that will track up into the Twin
Cities and eventually the Twin Ports region. We`re starting to get
hints of deep moist convection initiating, though to this point,
this feature has been fairly stable. However, with over 5000 j/kg
of MUCAPE up into western IA, persistent southerly flow will
continue to push more unstable air northward, so agree with the
HRRR and HopWRFs that we will eventually a cluster of storms
develop that moves north through the Twin Cities later this
afternoon. Again, with the better instability and shear off to the
southwest, these storms look to remain sub-severe.
After this MCV moves through, attention turns to threat for where
storms develop along the warm front. This next round of storms
will tap into the extreme instability down across IA, but there
continues to be little continuity in the models with where this
batch of rain ends up. For example, the HRRR between 12z and 18z
look fairly similar, the only difference is the 12z HRRR had the
evening/overnight storms from south central MN up into the Twin
Cities, while the 18z shifted it all north, with the heavy rain
from the Twin Cities/east central MN into northwest WI. At this
point, still favor a more southern solution like what the 12z
HREF and 15z HopWRF mean have, with the warm front ending up from
about Marshall to the MN/WI/IA border, with the greatest heavy
rain and severe risk through the night centered closer to that
region. Both the 12z and 18z HRRR show the potential for training
of storms along where the warm front sets up, with some areas
receiving 3+ inches of QPF. Fortunately, antecedent soil
conditions are dry, so really think to have much of a flash flood
threat, we`re going to need to see heavy rain in the urban core of
the Twin Cities metro. Everywhere else, soils are dry enough to
handle some good rains.
For the severe threat, that again looks better closer to the MN/IA
border, where instability will be greater and shear is increased
by the jet streak currently apparent on satellite imagery over KS
moving up over IA this evening. For the severe threat to
materialize, we probably need the souther solution to work out
(12z HRRR). If we see a more northern solution as we are seeing
with the 18z HRRR and the 18z HopWRF members just rolling in,
we`ll likely have a lower severe threat as these areas will be
displaced from the stronger instability and shear.
This activity tonight will likely generate an MCV, that will then
serve as the focus for thunderstorm development Monday afternoon.
There was certainly a trend from the GFS/NAM for the MPX area to
be hot and capped on Monday, but like the idea of the 18z HRRR.
Because of where it develops convection tonight, the HRRR
generates an MCV near the Twin Cities, that by Monday afternoon is
up by Duluth, with storms initiating there then tracking
southeast into western WI. This should be how things play out,
it`s just a matter of where that MCV ends up and given uncertainty
with where that will be, have kept PoPs mainly in the 30s north
of I-94. As you get southwest of I-94, you will be encountering
stronger and stronger capping, so have a dry day for Monday by the
time you get to south central, southwest, and west central MN.
With the lower cloud cover and drier conditions expected, this
will translate to hot conditions southwest of I-94, with
afternoon heat indices forecast to be in the mid 90s to lower
100s. Haven`t issued any heat headlines yet until we get a better
handle on how clouds and convection will trend Monday afternoon,
but a heat advisory is looking pretty likely for at least the Twin
Cities metro on Monday.
.LONG TERM...(Tuesday through Sunday)
Issued at 401 PM CDT Sun Jun 28 2020
For the long term, Tuesday is looking hot and dry, with the best
forcing for precip out in the Dakotas. Wednesday/Wednesday night
still looks to feature the passage of a weak cold front, but both
the GFS/ECMWF trended drier with it. This makes sense as the main
upper wave forcing this front will be going from the Dakotas into
northern Saskatchewan. So forcing and shear will be weak across
the MPX area with the front, with the severe threat really driven
by the presence of strong instability along the front.
Behind the front we see building heights and a drying trend
for Thursday through Saturday. Stuck with NBM PoPs for Thursday,
though those look overdone. Really it doesn`t look like we have
much of precip threat until Sunday, when a weak cold front looks
to drop down from the north. For temperatures, it still looks hot,
with the potential for us to pile on quite a few 90+ degree highs
through the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 700 PM CDT Sun Jun 28 2020
MCV moving through now bringing an initial round of storms. Still
some uncertainty with where the next round develops. The HRRR has
been bouncing around with where storms develop through the rest of
the night, but it has been bouncing additional storm development
around east central MN and western WI. Kept the similar theme
going with previous TAFs, but there`s still plenty of potential
for things to work out differently. Looks like MVFR cigs are going
to be confined closer to the MCV circulation in central MN, so
kept MVFR mention confined to AXN/STC, with models trending away
from MVFR or lower cigs elsewhere. For Monday, the trend
continues to be for drier conditions, with best TS potential in
WI, but confidence in TS occurring is not high enough to include
in the TAFs.
KMSP...MCV related precip will be off the field by 1z. After that,
it`s wait and see if we get another round. That next round looks
to get going near or shortly after 6z, possibly persisting out to
12z Monday. CIG trends have been to back away from MVFR potential,
so kept MSP VFR outside of TSRA, with a SCT cloud group at the
MVFR to handle that threat.
/OUTLOOK FOR KMSP/
Tue...Mainly VFR. Slight Chc TSRA/MVFR. Wind SE 15G25 kts.
Wed...Mainly VFR. Chc TSRA/MVFR. Wind SE 5-10 kts.
Thu...Mainly VFR. Chc TSRA/MVFR. Wind lgt and vrb.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&
$$
SHORT TERM...MPG
LONG TERM...MPG
AVIATION...MPG
Area Forecast Discussion
National Weather Service Marquette MI
717 PM EDT Sun Jun 28 2020
.SHORT TERM...(This evening through Monday)
Issued at 258 PM EDT SUN JUN 28 2020
Water vapor imagery and RAP analysis show a mid-level trough
deepening into the Pacific NW. Downstream, a ridge is building
through the Upper Mississippi Valley to Hudson Bay while a trough
extends from eastern Canada into the ne U.S. Sfc high pres
associated with the mid-level ridge extends from Hudson Bay
southward across the western Great Lakes today. Higher dew points in
the mid to upper 50s along with steep sfc-850 mb lapse rates has led
to some diurnal cu forming across much of interior U.P. this
afternoon. Temps thus far have generally reached into the lower to
mid 80s across the interior with cooler readings in the mid to
upper 70s near the Great Lakes shores due to lake breezes and
onshore flow.
Tonight into Monday, mid-level ridge will continue to build tonight
with the axis slipping very slightly eastward. Over the last few
days, the main question for the first part of this week has been
whether shortwaves lifting through the Plains will be able to cut
into the ridge or will be deflected around it. That process begins
tonight as the first shortwave, now over SD/IA, lifts ne. For
several days the GFS has generally been the most aggressive of the
models with the wave cutting into the ridge, but now it appears
other many of the other models are falling in line with the GFS,
bringing rain into at least the western third of the U.P. tonight
into Monday. Instability of MUCAPE values of 1000-1500 j/kg and lift
at the nose of 25-30 knot LLJ will aid development of possible
thunderstorms, although with weak deep-layer shear forecast strong
storms are unlikely. Will continue to include chance to slight
chance pops into the western third of the U.P. late tonight into
Monday.
Min temps tonight will range from the lower 50s interior east to the
lower 60s for southerly flow downsloping locations along Lake
Superior west and north central. Max temps on Monday under mostly
sunny to partly cloudy skies will be well into the 80s over much of
the interior with lake breezes keeping temps cooler near the Great
Lakes, in the mid to upper 70s.
.LONG TERM...(Monday night through Sunday)
Issued at 316 PM EDT SUN JUN 28 2020
...VERY WARM TO HOT CONDITIONS WITH HIGH HUMIDITY THIS WEEK...
Omega pattern across the US and southern Canada will dominate the
pattern through the middle of the week. This pattern will position
an anomalously high upper level ridge centered over Hudson Bay but
extends southward toward the Gulf Coast and US/Mexico Border.
Further west, deep anomalous troughing over the western CONUS will
likely surge shortwaves northward across the Central Plains into
Canada early in the period and depending on the strength and
position of the ridging, there could be an opportunity for precip in
the western UP. Toward the end of the week, deep troughing to the
west is progged to relax as ridging extends further west,
essentially encompassing much of the central and western CONUS by
Thursday and Friday.
The main story this week will be the heat. The weak mid-level
steering flow will allow 850mb temperatures to remain around 18-20C
through the week. As a result, day time highs in the upper 80s and
low 90s will be possible through the week. We may even challenge
some extended heat records this week. By the lakeshores, temps
should be a little cooler, especially on Thursday when northerly
flow off Lake Superior is expected. Dewpoints will also be on the
high side, with some guidance suggesting very uncomfortable,
sometimes borderline oppressive Tuesday and Wednesday in the west.
Given overnight lows in the low to mid 60s coupled with the high
dewpoints, very little overnight relief should be expected. It`ll be
important this week for folks and our four legged family members to
stay hydrated!
Model guidance continues to show a shortwave trying to undercut the
upper level ridging just to the west on Monday. Much of Monday night
will largely depend on the status of this wave and how effective
this push will be. For the moment, guidance suggests convective
pulsey thunderstorms will be possible in the far western UP and the
western portions of Lake Superior. Given the aforementioned weak mid-
level flow, weak shear profiles are expected and severe weather
isn`t a primary concern; the caveat being the amount of CAPE could
certainly be enough to support some healthy updrafts. The bigger
hazard associated with any shower or thunderstorm activity will be
rainfall. With the increasingly moist airmass settling over the west
and model guidance suggesting PWATS greater than or equal to 1.75
inches, heavy rainfall will be possible. Upper level ridging and
weak steering flow will slow the northward progression of this low,
keeping persistent chances of precip in the west through Tuesday
night. High pressure over eastern Lake Superior into Lower Michigan
will keep the east largely dry during this time. Beyond Tuesday,
this high will gradually shift west. Other then a chance of some
thunderstorms on Thursday, this looks to keep the region mainly dry
for the remainder of the week.
At the moment, the overall pattern suggests the very warm and hot
conditions will continue through the upcoming holiday weekend. In
terms of shower and thunderstorm activity, we`ll have to keep tabs
on how a shortwave moving through Canada will evolve on Saturday
through Sunday. Its possible that we could have some thunderstorm
activity Saturday into Sunday, but given the guidance`s lack of
consistency, confidence is pretty low.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 716 PM EDT SUN JUN 28 2020
VFR conditions at KIWD/KCMX/KSAW are expected thru this fcst period.
Winds at the sfc for KIWD, KCMX, and KSAW will be 10 kt or less
until a little bit past noon for KSAW, when winds could gust closer
to 20 kt. Also, KIWD could very well expect some on-and-off LLWS
between 04z to 12z. Still have reservations on whether shra/tsra
happens near KIWD, as models are not all in agreement. However,
there is enough confidence that shra/tsra will be approaching KIWD
early Monday morning to warrant at least a VCTS. If a TS or SHRA
does occur over KIWD, vis and cigs could rapidly deteriorate.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 258 PM EDT SUN JUN 28 2020
Through midweek, sfc high pres will ridge back from southeast Canada
into the Great Lakes while a low pres trough drifts out over the
Plains. A relatively weak pres gradient will result in winds under
20kt across Lake Superior over the next several days. However, there
may be locally enhanced winds each aftn/evening that may gust to 20-
25kt. Patchy fog noted on satellite imagery may persist into
tonight.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...JP
AVIATION...TAP
MARINE...Voss
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 325 PM CDT Sun Jun 28 2020
We are in a wait and see pattern if and when convection will
develop in our area. After this morning`s round of severe storms,
skies cleared out, but have also become partly to mostly cloudy
with daytime heating. An outflow boundary has triggered scattered
thunderstorms across south central IA, and satellite hints at this
possibly extending west into our area, with hints of some TCU
trying to develop between Plattsmouth and Tekamah. CAMs have
generally been all over the place this morning, initially keeping
storms out of the area, but the HRRR has lately indicated some
development between Omaha and Sioux City yet before 00z. There
isn`t much upper level support, so that may be a limiting factor.
The atmosphere is extremely unstable, with MLCAPE around 4000
J/Kg, but perhaps just slightly capped with less then 25 J/KG of
CIN. Best scenario is that something could develop in the
aforementioned area, and it`s within this area that SPC has also
continued the slight risk. There are also a couple of CAMs that
develop and MCS over northwest IA, and the tail end could ride
down the Missouri River valley late this evening and overnight, so
we`re not discounting that completely.
Meanwhile, the Saharan Dust layer arrived. It`s generally
undetectable on our various GOES16 dust products, but certainly
showing up in observations and pictures with visibility down to 5
miles in many locations. Airnow.gov indicates air quality is in
the moderate range in Omaha and in the unhealthful range for
sensitive groups in Lincoln. Hard to get a good handle on the
forecast for this, but a NASA model of Dust Aerosol Thickness
suggests some slight improvement by tomorrow. It`s also
incredibly humid out there with dewpoints in the mid to upper 70s,
making it feel like the mid to upper 90s. The dewpoint even hit
80 for one observation at Nebraska City at 155 pm.
Monday should be hot, humid, and dry. To match up with the NWS in
Sioux Falls, we will issue a heat advisory for Knox/Cedar counties
along the Missouri River where heat index value will range 100-105
during the afternoon.
There could be spotty nighttime convection Monday night on the
nose of the low level jet underneath the upper ridge. Not a clear
signal, but it`s only a 20% chance. Tuesday looks dry, and hot
and humid weather continuing. There remains a decent signal in the
models for storms increasing Tuesday night into Wednesday. But
it`s now looking dryer Thursday into Friday. Model blends indicate
a 20-30% chance for storms next Weekend. And while it`s the
holiday weekend, and we`d like to provide more definition, that`s
trending moreso toward climatology than anything at this point.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 632 PM CDT Sun Jun 28 2020
VFR conditions to prevail for the TAF period. Winds are currently
gusting up to 30 kts across the area including at KOMA and KLNK.
Wind speeds are expected to lower in the next hour or two. The
wind direction will remain southerly. There is a slight chance for
thunderstorms this evening over western Iowa and the Omaha area.
The probability isn`t high for this and will likely require a TAF
amendment to capture.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Heat Advisory from 1 PM to 7 PM CDT Monday for NEZ011-012.
IA...None.
&&
$$
DISCUSSION...DeWald
AVIATION...Fajman
Area Forecast Discussion
National Weather Service Shreveport LA
1042 PM CDT Sun Jun 28 2020
.UPDATE...
Only a few minor changes to forecast to account for current
trends. Otherwise, the remainder of the forecast remains the same.
A disturbance will move across the northwestern half of the region
tonight, providing forcing for showers and isolated thunderstorms
to continue during the overnight period. The best chances will be
across SE Oklahoma and along and north of the Interstate 30
corridor of NE Texas and SW Arkansas. Cloud cover will remain
across the region, limiting radiational cooling, so temps will
only fall a few more degrees into the mid to upper 70s tonight.
Winds to remain from the SSE between 5 to 10 mph. /20/
&&
.PREV DISCUSSION... /issued 758 PM CDT Sun Jun 28 2020/
AVIATION...
Scattered showers and a few isolated thunderstorms remain across
the region this evening, but VFR conditions have continued to
prevail. This activity should start to decrease in coverage by
04z with the exception being at Texarkana where showers/t-storms
may linger through 06z. Ceilings will become MVFR during the pre-
dawn hours and linger into the mid-morning across the terminals
before returning to VFR by late morning through the remainder of
the day. Additional scattered diurnal convection will be possible
by tomorrow afternoon at all the TAF sites. /20/
&&
PREV DISCUSSION... /issued 258 PM CDT Sun Jun 28 2020/
SHORT TERM.../Tonight through Monday Night/
The latest RAP mid-level analysis indicates that a 500mb high
pressure ridge is centered over the eastern Gulf of Mexico. The
local area is on the northwestern side of this feature in a
southwesterly mid-level flow. A weak short wave is sliding
northeastward into northeast Texas. At the surface, a 1019mb high
is located over the eastern Gulf with a broad area of high
pressure across much of the Southeast. Locally, on the west side
of this feature, the area is in a southerly low-level flow that is
continuing to advect a moist and humid air mass from the Gulf
into the area. Scattered showers and isolated thunderstorms have
developed with a few strong gusts in central Louisiana.
This evening, the mid-level short wave will continue to slide
northeast into southeastern Oklahoma. This feature will provide
forcing with strong instability in place (SBCAPE 3000-3500 J/kg),
allowing for scattered thunderstorms to continue across much of
the area. All members of the 12Z Storm Prediction Center (SPC)
High Resolution Ensemble Forecast (HREF) simulated radar support
that this with thunderstorms beginning to decrease late this
evening. In a weakly sheared environment, do not anticipate the
storms to become severe, although a few may become strong with
gusty winds possible. A surge of deeper moisture will move into
the area with PWAT values increase to near 2" into the evening
and thus a few of the storms are anticipated to have locally heavy
downpours which may lead to localized ponding in flood prone
areas.
One possible limiting factor for storms into the evening is any
remnants of the Saharan Air Layer, which will make for hazy
conditions with dust bringing visibilities to the 5-10SM range.
This layer of dust, which appears to be washing out and is
difficult to depict on satellite imagery, may assist in shortening
the lifespan of thunderstorms, maturing more quickly to their
dissipating stage and raining out. With all of this in mind, based
on current development moisture is deep enough to overcome any
suppression from the thinning Saharan Air Layer.
The short wave energy will shift further northeast of the area
overnight. This feature will provide forcing for some showers and
thunderstorms to continue overnight. In addition, with some
upstream convection in Texas that may push into our area as it is
weakening, have the chance of showers and thunderstorms continuing
overnight and becoming limited to southeastern Oklahoma,
northeastern Texas and southwestern Oklahoma by the pre-dawn
hours.
On Monday, the area will remain in a southwesterly mid-level flow
and will be in the wake of a short wave pushing northeastward into
the Missouri Valley. Forcing will be lacking for the most part
throughout the day with the hot and humid pattern continuing. Still,
strong instability should be sufficient for the development of at
least isolated diurnally driven thunderstorms. The best chance for
thunderstorms on Monday appears to be across southeastern Oklahoma
and southwestern Arkansas, where a short wave will pass to the
northwest. On Monday night, any lingering showers and
thunderstorms should diminish with yet another hot and muggy night
in the forecast.
For temperatures, it will be a warm and muggy night overnight
with lows in the mid to upper 70s. Highs on Monday are a degree
warmer than the NBM and will range from the mid 80s in McCurtain
County, Oklahoma to the lower 90s in East Texas, Deep East Texas,
and northern Louisiana. Heat indices will approach 100F across
much of the area with a few locations again coming near Heat
Advisory criteria of 105F. A Heat Advisory will probably not be
needed tomorrow as even locations that hit criteria today
probably will be just below criteria tomorrow. For an advisory it
is required to have two consecutive days of heat indices above
105F. Overnight lows on Monday night will be in the mid 70s across
much of the area. /04-Woodrum/
LONG TERM.../Tuesday through Sunday/
Upper level ridging over the Gulf of MX will begin to expand N
across TX and the Lower MS Valley Tuesday, and into the Midwest and
Mid MS Valley through Thursday, resulting in hotter temperatures as
we enter the month of July. A weak perturbation aloft may ride atop
the ridge Tuesday and may contribute to the development of isolated
convection over SE OK/SW AR/portions of Ncntrl LA, but the moisture
profile looks to remain shallow which may negate any development
over these areas. Did maintain slight chance pops over these areas
in the afternoon, which should diminish by sunset if they develop.
The main story though through the first half of the long term period
though will be the heat, with max temps likely reaching the mid 90s
over much of the area Tuesday through Thursday, with dewpoints
likely not mixing out much during the day given the stagnant pattern
in place and likely to persist. Thus, heat indices may be
approaching Heat Advisory criteria in some areas especially by
Wednesday and Thursday, with later forecasts continuing to refine
this threat. Any convection Wednesday will remain isolated at best
over portions of Scntrl AR/Ncntrl LA, but a weakness remains progged
by the ECMWF/GFS to develop over the Mid MS Valley Thursday before
sliding S along the Ern periphery of the amplifying upper ridge as
it expands into the Dakotas into the Nrn Great Lakes region. There
has been consistency amongst the progs the last couple of days with
convection developing along an attendant sfc trough Thursday
afternoon from Nrn OK into Ncntrl AR and the Mid-South region, with
this convection possibly building SSE across Ern OK through much of
AR through the evening, and thus have included low chance pops for
the Nrn and NE zones, with this convection possibly building into
the region Thursday night and Friday as this shortwave trough
continues to slide S.
Have maintained consistency with the previous forecast in
undercutting pops for now given that it is 5-6 days out, as this
convection will likely be diurnally and mesoscale driven, and have
trended low to mid chance pops over the region Thursday night
through Friday night. May also have to contend with compressional
heating Thursday afternoon across SE OK/Nrn sections of SW AR near
and just S of the approaching weak sfc trough, but believe the
convection Thursday night through Friday will alleviate the heat
somewhat while also resulting in slightly lower dewpoints. Could
still see sct convection persist across the region Saturday as the
sfc trough lingers over the area, with more isolated convection
Sunday as we become more influenced with the Ern extent of the large
Cntrl CONUS ridge. Should this weak troughiness cut off though over
the Lower MS Valley (as suggested by the 12z ECMWF/GFS), then a
continued unsettled weather pattern will persist for at least
portions of SW AR/N LA through the remainder of the holiday weekend
into the first full week of July.
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 77 92 76 93 / 20 30 10 10
MLU 74 91 74 93 / 20 30 10 20
DEQ 74 88 74 90 / 40 50 10 20
TXK 76 88 75 91 / 30 40 10 20
ELD 73 89 73 92 / 20 40 10 20
TYR 76 91 76 93 / 30 20 10 10
GGG 76 92 76 93 / 20 20 10 10
LFK 77 92 76 94 / 20 10 10 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
20